Jm. Mellor et al., SYNTHESIS OF FRAGMENTS OF TRANSFORMING GROWTH-FACTOR-ALPHA INCORPORATING EXO-2-AZABICYCLO[2,2,1]HEPTANE-3-CARBOXYLIC ACIDS AS PROLINE SUBSTITUTES, Tetrahedron letters, 36(37), 1995, pp. 6765-6768
Two novel amino acids, the enantiomers of exo 2-azabicyclo[2,2,1]hepta
ne-3-carboxylic acid have ben independently synthesized by the aza Die
ls Alder reaction using a chiral auxiliary. The two acids have been ad
vanced via solid phase synthesis to afford linear sequences, which hav
e been cyclized to afford cyclic disulfide peptides, analogues of frag
ments of TGF alpha. The structures of these and other fragments have b
een firmly established.